Radiodiagnostic apparatus including a pivotable x-ray table

ABSTRACT

A radiodiagnostic apparatus including a pivotable table made up from a panel for supporting a patient and a tomography device articulated on a pendulum system, the assembly being mounted on a vertical ring-shaped support rotatable about its own axis. The tomography system and the patent supporting panel are suspended substantially at their centers of gravity on carriages sliding along two parallel circular arc-shaped arms perpendicular to the vertical ring. A system for coordinating the movements of the different mobile components of the apparatus makes it possible to pivot the tomography system about the axis of the patient supporting panel, which remains stationary in space.

United States Patent 1191 Cesar Dec. 3, 1974 [5 RADIODIAGNOSTIC APPARATUS 3,670.163 6/1972 Lajus .7 250/320 INCLUDING A PIVOTABLE X-RAY TABLE Primary Examiner-James W. Lawrence [75] lnvemor' Jean Cesar Pans France Assistant ExaminerB. C. Anderson [73] Assignee: Compagnie Generale De Radiologie, Attorney, Agent, or FirmCushman. Darby &

Paris, France Cushman [22] Filed: May 1, 1973 21] Appl. No.: 356,139 [57] ABSTRACT A radiodiagnostic apparatus including a pivotable table made up from a panel for supporting a patient [30] Foreign Apphcatmn Pnonty Data and a tomography device articulated on a pendulum May 5, 1972 France 72.16106 System the assembly being mounted on a vertical ring shaped support rotatable about its own axis. The to- [52] U.S. Cl 250/445, 250/320, 250/490 mography system and the patent Supporting panel are [51] Int. Cl. G03b 41/16 Suspended substantially at their centers of gravity on [58] Field of Search 250/320, carriages sliding along two parallel circular arc-shaped 250/445, 492 arms perpendicular to the vertical ring. A system for coordinating the movements of the different mobile [56] References C'ted components of the apparatus makes it possible to UNITED STATES PATENTS pivot the tomography system about the axis of the pa- 1,9ss,715 12 1934 Bucky 250/322 tient Supporting Panel, which remains Stationary in 2,1 l0,954 3/1938 Grossmann 1 250/490 space. 2,167,! 15 7/1939 Keiffer 1 250/323 2,818,510 12/1957 Verse 250/490 7 Claims, 6 Drawing Figures PATENTL, BEE 31974 SHEET 20F 5 PATENH GEE 3|974 SHEET 30F 5 PATENTL EEC 31974 sum u or 5 v PATENTELBEB Si n 3,852,611

SHEET 5 [IF 5 RADIODIAGNOSTIC APPARATUS INCLUDING A PIVOTABLE X-RAY TABLE The present invention relates to radiodiagnostic apparatus having a pivotable X-ray table and concerns, in particular, such as those used as patient supporting means in a tomography apparatus. Radiodiagnostic apparatus of this kind has become widely used and is well known per se. They essentially include a table panel or plate, used to support the patient, and by a supporting structure rotationally carried for example by a ringshaped support located in a vertical plane. This disposition enables the panel to occupy any position between the horizontal and the vertical, in both senses. These devices furthermore generally comprise a mobile and pivotable column, utilised as a support for X-ray emissive devices at one end and for radiological image receivers at the other. The column and/or panel are moveable in the longitudinal direction of the panel in order to make it possible to irradiate any required point upon the latter.

Apparatus of this kind has a certain number of drawbacks and it is the object of the present invention to overcome these. A

The proximity of the column to the patient, creates in the latter a sense of anxiety which can result in movements of reaction at the time of exposure, while the column is pivoting (tomography), so that the quality of the X-ray picture is poor.

The various assemblies making up the X-ray apparatus, are almost always located at the same side of the main support, thus creating an unbalanced or overhung system which gives rise to problems of design as far as the production of a vibrationfree system is concerned. Moreover, because of distortions created by this overhung arrangement, the changes in the orientation of the table or of the pendulum or of both simultaneously,

produce misalignment; it is well known, for example,

that it is impossible to pivot the X-ray tube and image receiver system in just any direction, without losing image centering.

in prior art apparatus, tomography picture obtained thus their relative distances varied with-their angular position. In an apparatus in accordance with the invention, source and receiver are displaced over a sector of sphere'whilst the beam emanating from the source is always directed towards the center of the sphere, which center becomes therefore the center of tomography. The X-ray beam is consequently always located inside a cone whose apex is defined by this tomography centre.

The determination of the tomography plane, wherein the axis of the shaft pivotably carrying the column is located, requires observation along an axis perpendicular to the axis in which tomography is to be carried out. in the case of the prior art X-ray diagnostic apparatus, this resulted in displacements of the panel and/or the source which at the very least meant a loss of time and a certain amount of fumbling, quite apart from the nuisance caused to the patient. The arrangement of the novel apparatus makes it possible to position a second X-ray source, whose beam is permanently directed towards the tomography centre, perpendicularly to the axis of the above indicated cone, thus making it possimutually perpendicular axes and to locate the desired tomography plane in a highly accurate fashion.- The positioning of said second source is made possible, with the novel apparatus in accordance with the invention, by the fact that there is no support or component of any kind to interfere with the beam, whatever the configuration thereof.

Moreover, the novel apparatus makes it possible to irradiate the patient at any angle of incidence although he or she remains horizontal or immobile.

According to the invention there is provided, a radiodiagnostic apparatus for X-ray and, in particular, tomography examinations of a patient, including: a fixed base; a ring-shaped support located in a vertical plane and mounted on said base for rotation about a horizontal axis; two parallel circular arcuate arms extending perpendicularly to and mounted integrally with said ring-shaped support, said arcuate arms being located symmetrically in relation to the center of said ring shaped support and the centers of their radii defining a first axis perpendicular to said horizontal one; two first carriages respectively mounted on said arcuate arms for simultaneous translational displacements therealong; first motor means for controlling said displacement of said carriages; rigid beam-shaped supporting means parallel to said first axis for fixedly interconnecting said first carriages; a second carriage mounted on said beam-shaped supporting means for independent translational displacement therealong; fork-shaped supporting means fixedly mounted on said second carriage having at their respective ends a pair of first and second concentric shafts both coaxial with said first axis, said first shaft being the outer one; panelshaped patient supporting means mounted on said first shaft for rotation therewith about said first axis; second motor means carried by said second carriage for driving said first shaft in rotation; third motor means carried by said second carriage for driving said second shaft in rotation, said second shaft being coupled to a mechanism known per se for displacing said panelshaped means in parallel to itself; a third carriage mounted on said beam-shaped supporting means for independent translational displacement therealong; plate-shaped supporting means mounted integrally with said third carriage and extending away from said beamshaped means to the opposite side relatively to said fork-shaped means; an elongated supporting system mounted on said plate-shaped means for omnidirectional pivoting about a plane parallel thereto; an X-ray source and an X-ray image receiver means respectively articulatedly mounted to both ends of said elongated system for respective location on either side of a patient placed on said panel-shaped supporting means, said X-ray source emitting an Xray beam whose axis always intersects with said first axis and is incident on the center of said image receiver means; whereby the center of gravity of the assembly carried by said first carriages will always be located in the vicinity of said beam-shaped means.

The invention will be better understood and other of its features and advantages rendered apparent, from the following description and the accompanying drawings, wherein:

FIG. 1 is a front elevational view of the novel X-ray apparatus;

FIG. 2 is asectional side elevational view of the apparatus in the position corresponding to frontal X-ray projection;

FIG. 3 is a plan view of the apparatus when in horizontal position,

FIG. 4 is a lateral view of the arcuate track 11 with its supporting carriage;

FIG. 5 is a sectional view of the supporting means;

FIG. 6 is a side elevational view of the apparatus in the tomography configuration.

In FIGS. 1 and 2, a metal ring 1, vertically supported by a set of rollers 2 upon which it can roll, can be seen. These rollers are journalled to the floor 3 by means of a frame or wall which has not been shown. The rotation of the ring 1 on the rollers 2 is controlled by a fixed chain, shown in broken line, winding around a sprocket 4 driven by a reduction gear box and a motor 5. The ring 1 can thus rotate both clockwise and anticlockwise, and can be displaced through an amplitude in excess of half a turn 180) to either side of a central position.

The assembly of the apparatusmounted on this ring 1 by means of two circular arcuate components l 1 subtending an angle of around 160. These arcs 11 are attached in perpendicular relationship to the ring 1, parallel to each other, by means of two mounting components 51 and 52 located symmetrically with respect to the center of the ring and integral therewith. The

mounting components 51 and 52 fixedly carry the arcs 11, which, in turn slidably carry carriages 7 (FIGQ4).

In said FIG- 4, a carriage 7slida-bly mounted, in a manner known per se, on the are 11 by means of rollers 8, can be seen, the displacement of the carriage 7 along the arc being controlled by a fixed chain, marked in broken-line and winding about a toothed sprocket 9 driven by motor and reduction gear assembly and journalled to the carriage '7. Thetwo carriages 7, respectively sliding on each of the arcs 11 are connected together, on the one hand, through two beams 12 and, on the other hand, through a polygonal shaft 10, one end of which has been shown in square form in FIG. 4, passing through the sprocket 9. In this fashion, the two sliding carriages 7 are secured to one another and are at all times located at homologous positions on each of the arcs 11, because of the fact that the sprockets 19 controlling their displacements themselves have identical positions due to the shaft 10 which links them.

Along these connecting beams 12, there are displacedtwo carriages 13 and 22 (FIG. 3), the carriage 13 carrying, towards the interior of the ring 1, a column assemblywhich will be described hereinafter, and the carriage 22 carrying, towards the opposite side, a forked-shaped support 21 for supporting a panel for the patient or table top 23. These two carriages 13 and 22 are moveable along the beams 12 independently of one another so that thesource located substantially at the center of the carriage 13 can irradiate one orthe other of the two ends of the panel 23.

I Considering FIG. 2, a plate 24 can be seen, which is integrally fixed to the carriage l3 and which, by means of bosses 25 containing ball joints or the like, carries three levers 14. The structure of the plate 24 is such that the plane defined by said three ball joints passes through the center of the circular arcs 11. The three lever's 14 are maintained parallel with one another and hinged together in three planes made up by means of rigid links schematically represented at 16, 17 and 18. The rigid structures 16 and 17 are extended throughout and towards the other side of the ring 11, i.e., to the side opposite to the support 24, and carry the receiver 28 (fluoroscopic screens, cameras and/or image intensifier with accessories) and the main X-ray source 15. The X-ray source 15 is integrally fixed to a rigid link schematically illustrated at 26, which is coupled in an articulated manner to at least two levers 14 through a rigid link 27 and the extension of link 16. It would be seen that when the levers 14 are inclined, any point on the links 16 and 17 will move over the surface of a sphere, the center of this sphere being located in the plane defined by the three points of articulation (25) of the levers to the plate 24.

The source 15 fixed to link 26 is maintained parallel to the levers 14 by means of a structure 27 attached by ball joints to at least two of these. It will be seen that the structure 26 is at all times aligned with a fixed point in relation to the support 24. The extensions or suspension arms of the structure 16 and 17, have a length such that the centres of the spherical sectors described by the source 15 on the one hand and the receiver on the other, are coincidental with one another and located upon the straight line joining the centers of the circular arcs 11. The source 15 fixed to the structure 26, is

therefore permanently trained on a fixed point in relation to the. support 24, and situated on said same straight line. This point will in all cases be the tomography centre.

The structure 18, articulated to the same three levers 14, is connected by a rigidextension 29 to the tomography control plate of known kind. It comprises a threaded rod 30 axially driving a nut carrying a shaft hinged to the rigid extension 29. The rod 30 is journalled to a plate 31 which can pivot about a pin perpendicular to and fixed to the plate 24. An electric motor 32 attached to the plate 31 drives the threaded rod 30. On the other hand, the plate 31 carrying the rod-30 is itself rotated by a motor 33 about the aforementioned pivot of support 24. It will be seen that by' these means,

through coordination of the movements of the motor 32 and 33, the link 18 andconsequently the source 15, can be imparted an absolute motion of any kind over the surface of a sphere, which motioncanfor example be a circular arc in any desired direction, a circle, a spiraletc, while the source 15 remains at all times directed upon a fixed point in relation to the support plate 24. The X-ray beam is therefore at all times displaced within a cone the centre of which is fixed in relation to the plate 24 and is located upon the straight line joining the centres of the arcs l l. The angles subtended at the apex of the cone is equal to the angle of inclination at which the levers 14 are capable.

The carriage 13 furthermore carries an auxiliary source 20 on an arm 19. The beam from this source is directed permanently on to the apex of the cone of oscillation of the main source 15, perpendicularly to the axis of said cone. Considering FIGS. 2 and 3, it will be seen that the beam from the source 20 passes, on the one hand, between two articulated levers 14, and, on the other hand, between'the two beams 12. Thus, there is no dead angle as far as this beam is concerned (nor is there any in respect of the beam produced by the source 15) at any position of the carriages 7 and-13.

A forked-shaped support 21 is fixed at the patient support plate side' to the second-carriage .22, which slides along the connecting beams 12. This support 21 carries the patient support panel 23 through two coaxial pivots 34 and 35 whose purpose will be explained hereinafter. The axis of suspension of the panel, i.e., that of pivots 34 and 35, is coincidental with the straight line joining the centers of the two arcs 11. The result is that displacements of the carriages 7 along the arcs 11, produces displacement of the fork 21 and of the support 24 and, with the latter, displacement of the source of the receiver 28, in a rotational manner about an axis which is fixed in relation to the arcs 11. In FIG. 2, a broken line has been used to indicate the respective positions 121, 151 and 281 of the carriages 7, source 15 and receiver 28, after displacement of said carriages to the ends of the arcs 11.

However, although the carrier pivots 35 of the patient support panel (FIG. 5) remain stationary in space during displacements of the carriages 7 along the arcs 11, they nevertheless undergo rotation. It is necessary to avoid this rotation by counteracting it so as to maintain the panel 23 parallel to itself during displacements of the carriages 7 along the arcs 11. Moreover, the panel 23 must be capable of being displaced perpendicularly to its own plane so that the tomography plane can be selected (and varied). It has been seen that the determination of the desired tomography plane is greatly aided by the utilisation of the auxiliary source the beam from which is always directed onto the center of the arcs 11 perpendicularly to the axis of the cone within which the beam produced by the main source 15 can be displaced. It is likewise important that during displacements of the carriages 7 along the arcs 11, not only does the panel 23 remain parallel to itself, but neither should its position in relation to the center of tomography which is fixed, vary. This maintaining of the panel 23 in a fixed position in space, both in rotation and translation, during displacements of the carriages 7, isobtained by means of a mechanical arrangement schematically shown in FIG. 5.

At 21, the support of forked shape for carrying the panel 23 upon which the patient lies, can be seen. The two ends of the fork each carry two concentric shafts 34 and 35, the shafts 34 supporting the frame of the panel (not shown) and the shaft 35 controlling the displacement of the panel in the direction perpendicular to its own plane, by means of a known mechanism (likewise not shown). The rotation of the shaft 34, and consequently the panel, is controlled by a motor and reduction gear set 37, to which said shaft is connected through a chain 46 meshing with the sprockets 44. The shaft 35 is rotated in the same manner by the motor and reduction gear set 38, driving the chain 37 meshing with the sprockets 45 which have the same diameter as those 44. The two sets 37 and 38 are assembled on slides or the like and can be displaced along the support 21, displacing the chains 46 and 47, which respectively control the rotation of shafts 34 and 35, as they do so.

onal shaft 10 connecting the sprockets 9 of the two carriages 7 (FIG. 4) during translational movements of the latter. The dimensions of the various sprockets and the threading of the shaft 39, are designed so that the displacement of the carriages 7 along the arcs 11, produces' displacement of the set 37 and consequently of the chain 46 controlled by it, by an amount and in a direction such that the shaft 34 in relation to the support 21 performs a rotation equal and opposite to the rotation of the forks of support 21 during displacement of the carriages 7 along the arcs 11.

The shaft 35 controlling translation of the panel 23 perpendicularly to its own plane, should not rotate in relation to the panel (and therefore in relation to the shaft 34), either during this movement of the carriages 7 or when the operator initiates rotation of the panel 23 by means of the motor and reduction gear set 37. This double effect is obtained by fixing the set 38 (mounted on slides like the set 37) to the chain 46 controlling rotation of the shaft 34. To do this, the chain 46 is attached to the set 38 by means of a wedge arrangement 42. It will be seen that in these circumstances, on the one hand, when the set 37 is displaced by the movement of the carriages 7 over the arcs 11 and, on the other hand, when the set 37 is set into operation to manipulate the panel 23 through the shaft 34, the chains 46 and 47 are displaced by the same amount, causing the shafts 34 and 35 to execute the same angle of rotation since the sprockets 44 and have the same diameters, in other words, during these two operations, the panel 23 remains parallel to itself and executes no displacement perpendicular to its own plane since the shaft 35 remains stationary in relation to the shaft 34.

The panel 23 furthermore comprises a lateral translation device, this being a device well known per se and not having been illustrated here since it does not affect the invention.

It will be seen that the aforedescribed arrangements of the apparatus result first of all in better balancing of the system. The moving weights carried by the carriages 7 are in other words distributed to either side of said carriages: panel and patient at one side, assembly of sources and receiver, at the other. The improvement in balance is achieved not only in relation to the beams 12, but also in relation to the suspension of the entire system on the ring 1, which results in a simplification of the structure and lower weight, a reduction in distortion and improvement of motion which becomes substantially vibrationless. Moreover, the patient no longer has the oscillating levers for the tomography operation close to his sides, these being separated from him by the beams 12. The various panel supports occupy fixed positions in relation to the sources and receivers so that there is no longer any dead angle to be avoided when it is desired to change the angle of incidence. The preparatory work for X-ray examinations is therefore much simplified and operation become much faster. Another advantage of this arrangement of the supports is that it makes it possible to install the second source 20, the usefulness of which has been described hereinbefore. Finally, the system for coordinating the movements of the panel supporting the patient makes it possible to give the two beams all the possible angles of incidence without modifying the position of the panel and the tomography plane. 1

The device for carrying the patient supporting panel can be designed so that it can be removed and replaced by another equivalent one or one having different characteristics. These characteristics may be ones pertaining to its type and shape. The panel can be replaced by an interchangeable device equipped with one or two lengthwise members Carrying an articulated panel which may for example be turned into a chair for neurological applications.

This X-ray apparatus is also particularly well suited for neurological examinations because the beam and the patient can be pivoted by means of the main ring, through at least 180 to either side (gas encephalography) without changing there relative positions.

Finally, it is possible with this equipment to use elements other than the panel hereinbefore described, such for example as chairs, and horizontal tables with moving panels. These elements can be fixed or mobile on the floor, or to that matter be fixed to the apparatus.

What is claimed is:

1. Radiodiagnostic apparatus for X-ray and, in particular, tomographic examinations of a patient, including: a fixed base; a ring-shaped support located in a vertical plane and mounted on said base for rotation about a horizontal first axis coinciding with that of the ring; two parallel circular arcuate arms extending perpendicularly to and having one of their ends secured integrally to .said ring-shaped supportat diametrically opposite locations thereof, said arcuate arms being located symmetrically in relation to the first axis and the centers of their radii defining a second axis perpendicular to said first axis; a pair of first carriages respectively mounted on said arcuate arms for simultaneous parallel displacements therealong; first motor means for controlling said displacements of said first carriages; rigid beamshaped supporting means parallel tosaid second axis fixedly interconnecting said first carriage pair; a second carriage mounted on said. beam-shaped supporting means for independent translational displacements therealong; fork-shaped supporting means fixedly mounted on said second carriage having at their respective ends: a pair of first and second concentric shafts both coaxial with said second axis, said first shaft pair being the outer one; panel-shaped patient supporting means having ends respectively secured to said first shaft pair for rotation therewith about said second axis; second motor-means carried bysaid second carriage for driving-said first shaft pair in rotation; third motor means carried by said second carriage for driving said second shaft pair in rotation, said second shaft pair being coupled to means for displacing said panelshaped supporting means in parallel to itself; a third carriage mounted on said beam-shaped supporting means for.indep'endent translational. displacements therealong parallel tothe displacements of said second carriage; plate-shaped supporting means mounted integrally with said third carriage and extending away from said beam-shaped means to thevopposite side relatively by said first carriage pair will always be located in the vicinity of said beamshaped means.

2. Apparatus as claimed in claim 1, wherein said elongated supporting system comprises: three lever rods journaled respectively by means of joints allowing omnidirectional pivoting, of the type of ball-or cardanjoints, on said plate shaped means, said joints being located at the edges of a triangle in a plane containing said second axis; a first and a second connecting means articulated by means of omnidirectionally pivoting joints at the respective ends of said levers, for maintaining said levers parallel to each other whatever their inclination relative to said plane containing said second axis; a first rigid arm member integral with said first connecting means and extending towards that side of the beam-shaped means where said panel-shaped means is located for carrying said X-ray image receiver; a paralellogram-type structure including: a second rigid arm member integral with said second connecting means and extending towards that side of said beam-shaped means where said panel-shaped means is located; stub portions prolongating at least two of said three levers above said second connecting means by a predetermined length; a third elongated arm member omnidirectionally articulated on atleast two of said stub portions; a rigid rod-shaped member of said predetermined. length and omnidirectionally articulatedly connecting together the free ends of said second and thirdarm members so as to always be oriented in parallel to said levers; said X-ray source being integrally mounted on said rod-shaped connecting member so as to always direct said X-ray beam to intersect with said second axis; whereby said X-ray source is displaceable along a sphere and the X-ray beam within a cone whose apex constituting the center of said sphere always lies on said second axis.

3. Apparatus as claimed in claim 2, further comprising means for controlling the pivoting said lever rods and wherein said means'for controlling includes: third rigid connecting means identical and parallel to said first and second ones and located at a predetermined distance from said plane containing said second axis; a third arm member integral with said third connecting means and having a free end protruding therefrom towards the opposite side to that of said first and second arm members, said free end carrying a bearing; a threaded shaft and nut assembly lodged on a flat supporting plate, said threaded shaft being driven in rotation by means of fourth motor means carried by said flat plate and said nut carrying a third shaft engaging in said bearing; a fourth shaft extending from and perpendicularly to said plate-shaped supporting means for rotatably carrying said flat plate; and fourth motor means carried by said plate-shaped means for rotating said flat plate, whereby to enable said X-ray source be displaced in any desired direction on said sphere surface such as along circular are, a circle or a spiral.

4. Apparatus as claimed in claim 2, wherein a second auxiliary X-ray source is rigidly mounted on said plateshaped support for emitting a second X-r'ay beam whose axis intersects with said second axis at the apex of said cone.

5. Apparatus as claimed in claim 1, wherein said' first motor means for controlling the displacement of said first carriage pair along said two arcuate arms include a polygonal shaft for interconnecting said first carriage pair and for synchronising its movements.

6. Apparatus as claimed in claim 5, wherein said first outer shaft pair for rotating said panel-shaped supporting means respectively carry a pair of first sprockets; said second motor means having a fifth shaft carrying a second sprocket; a first endless chain meshing with said first and second sprockets; and wherein said second motor means is carried movably on said forkshaped means in a first pair of slides, the displacement of said second motor means along said first slide pair being controlled by means of a further threaded shaft journalled on said fork-shaped means and a nut engaging with said second motor means, said further threaded shaft being coupled to said polygonal shaft by means of a second endless chain and a pair of third sprockets, whereby said first shaft pair carrying the pa- 7 nel-shaped supporting means is rotated synchronously with the displacement of the first carriage pair along the arcuate arms so as to maintain said patient in a fixed position in space whatever the position of said first carriage pair along said arcuate arms.

7. Apparatus as claimed in claim 6, wherein said second inner shaft is driven by said third motor means by means of a pair of fourth sprockets and an third endless chain, said fourth sprockets being of the same size a said first sprockets; said third motor means being freely movably mounted on said fork-shaped means for displacement along a second pair of slides parallel to said first pair of slides and connected to said second endless chain, whereby to render said second shaft pair stationary with respect to said first shaft pair, on the one hand, when said first carriages are displaced along said arcuate arms and, on the other hand, when said first shaft pair is rotated by means of said second motor means. =l l 

1. Radiodiagnostic apparatus for X-ray and, in particular, tomographic examinations of a patient, including: a fixed base; a ring-shaped support located in a vertical plane and mounted on said base for rotation about a horizontal first axis coinciding with that of the ring; two parallel circular arcuate arms extending perpendicularly to and having one of their ends secured integrally to said ring-shaped support at diametrically opposite locations thereof, said arcuate arms being located symmetrically in relation to the first axis and the centers of their radii defining a second axis perpendicular to said first axis; a pair of first carriages respectively mounted on said arcuate arms for simultaneous parallel displacements therealong; first motor means for controlling said displacements of said first carriages; rigid beam-shaped supporting means parallel to said second axis fixedly interconnecting said first carriage pair; a second carriage mounted on said beam-shaped supporting means for independent translational displacements therealong; fork-shaped supporting means fixedly mounted on saiD second carriage having at their respective ends a pair of first and second concentric shafts both coaxial with said second axis, said first shaft pair being the outer one; panel-shaped patient supporting means having ends respectively secured to said first shaft pair for rotation therewith about said second axis; second motor means carried by said second carriage for driving said first shaft pair in rotation; third motor means carried by said second carriage for driving said second shaft pair in rotation, said second shaft pair being coupled to means for displacing said panel-shaped supporting means in parallel to itself; a third carriage mounted on said beam-shaped supporting means for independent translational displacements therealong parallel to the displacements of said second carriage; plate-shaped supporting means mounted integrally with said third carriage and extending away from said beam-shaped means to the opposite side relatively to said fork-shaped means; an elongated supporting system mounted on said plate-shaped means for omnidirectional pivoting about a plane parallel thereto; an X-ray source and an X-ray image receiver means respectively articulatedly mounted to both ends of said elongated system for respective location on either side of a patient placed on said panel-shaped supporting means, said X-ray source emitting an X-ray beam whose axis always intersects with said second axis and is incident on the center of said image receiver means; whereby the center of gravity of the assembly carried by said first carriage pair will always be located in the vicinity of said beamshaped means.
 2. Apparatus as claimed in claim 1, wherein said elongated supporting system comprises: three lever rods journaled respectively by means of joints allowing omnidirectional pivoting, of the type of ball-or cardanjoints, on said plate shaped means, said joints being located at the edges of a triangle in a plane containing said second axis; a first and a second connecting means articulated by means of omnidirectionally pivoting joints at the respective ends of said levers, for maintaining said levers parallel to each other whatever their inclination relative to said plane containing said second axis; a first rigid arm member integral with said first connecting means and extending towards that side of the beam-shaped means where said panel-shaped means is located for carrying said X-ray image receiver; a paralellogram-type structure including: a second rigid arm member integral with said second connecting means and extending towards that side of said beam-shaped means where said panel-shaped means is located; stub portions prolongating at least two of said three levers above said second connecting means by a predetermined length; a third elongated arm member omnidirectionally articulated on at least two of said stub portions; a rigid rod-shaped member of said predetermined length and omnidirectionally articulatedly connecting together the free ends of said second and third arm members so as to always be oriented in parallel to said levers; said X-ray source being integrally mounted on said rod-shaped connecting member so as to always direct said X-ray beam to intersect with said second axis; whereby said X-ray source is displaceable along a sphere and the X-ray beam within a cone whose apex constituting the center of said sphere always lies on said second axis.
 3. Apparatus as claimed in claim 2, further comprising means for controlling the pivoting said lever rods and wherein said means for controlling includes: third rigid connecting means identical and parallel to said first and second ones and located at a predetermined distance from said plane containing said second axis; a third arm member integral with said third connecting means and having a free end protruding therefrom towards the opposite side to that of said first and second arm members, said free end carrying a bearing; a threaded shaft and nut assembly lodged on a flat supporting plate, said Threaded shaft being driven in rotation by means of fourth motor means carried by said flat plate and said nut carrying a third shaft engaging in said bearing; a fourth shaft extending from and perpendicularly to said plate-shaped supporting means for rotatably carrying said flat plate; and fourth motor means carried by said plate-shaped means for rotating said flat plate, whereby to enable said X-ray source be displaced in any desired direction on said sphere surface such as along circular arc, a circle or a spiral.
 4. Apparatus as claimed in claim 2, wherein a second auxiliary X-ray source is rigidly mounted on said plate-shaped support for emitting a second X-ray beam whose axis intersects with said second axis at the apex of said cone.
 5. Apparatus as claimed in claim 1, wherein said first motor means for controlling the displacement of said first carriage pair along said two arcuate arms include a polygonal shaft for interconnecting said first carriage pair and for synchronising its movements.
 6. Apparatus as claimed in claim 5, wherein said first outer shaft pair for rotating said panel-shaped supporting means respectively carry a pair of first sprockets; said second motor means having a fifth shaft carrying a second sprocket; a first endless chain meshing with said first and second sprockets; and wherein said second motor means is carried movably on said fork-shaped means in a first pair of slides, the displacement of said second motor means along said first slide pair being controlled by means of a further threaded shaft journalled on said fork-shaped means and a nut engaging with said second motor means, said further threaded shaft being coupled to said polygonal shaft by means of a second endless chain and a pair of third sprockets, whereby said first shaft pair carrying the panel-shaped supporting means is rotated synchronously with the displacement of the first carriage pair along the arcuate arms so as to maintain said patient in a fixed position in space whatever the position of said first carriage pair along said arcuate arms.
 7. Apparatus as claimed in claim 6, wherein said second inner shaft is driven by said third motor means by means of a pair of fourth sprockets and an third endless chain, said fourth sprockets being of the same size a said first sprockets; said third motor means being freely movably mounted on said fork-shaped means for displacement along a second pair of slides parallel to said first pair of slides and connected to said second endless chain, whereby to render said second shaft pair stationary with respect to said first shaft pair, on the one hand, when said first carriages are displaced along said arcuate arms and, on the other hand, when said first shaft pair is rotated by means of said second motor means. 